MOT Problems, MK3 VR6

[jafo]

Hi i have a mk3 VR6 98' and have had it for about 4 months now, When i first brought it the abs wasnt working, i took it to a friends and he put it on his snap on machine, it told me the faults and i changed the abs sensors which one only works intermitently so i think its the pump, but never mind that i mod'd the abs/airbag light unit and its passed on that, andother fault was the o2 sensor, so i changed that too. Since changing i have not cleared the fault codes again though.
I put it into mot 2 weeks ago now it failed on emmisions, exhaust blowing from centre box, strut top mounts, and braking effieceny, well i got to work, put it on a ramp at my work and changed both strut top mounts in about 25 mins even though it only failed on one, took the pads and discs off gave them a good clean up, and got a friend to make me a cat back s/s exhaust system, since this i have put it back into mot today and they said its still failing on exhaust emmisions although it has improved.
I asked more about it and he couldnt say what was causing this just that its running too rich.
My inital thought was that i didnt clear the codes after replacing the o2 sensor, but surely the ecu would adjust once it realised it was working again??
Please help me  or tell me things to try just to get it through mot then il get whatever it is sorted! As its really winding me up now!
Thanks

[jafo]

Do these have two o2 sensors??

[saul79]

not sure about that thought they just had one my mates is 96 and has one .

[jafo]

well just looking at my emissions sheet and its failed on fast idle, the co is at 0.585 and max limit is 0.300, is this out by much? Any possible causes? The hydro carbons and lambda are ok just the co level its failings on, its fine at idle just the problem when its fast idling! Please help me.

[zorro]

When you changed the Lambda sensor - did you use a genuine VW one?
If you didnt then my money is on your sensor failing again - non VW ones are renowned for it.

I made the same mistake on my VR.

HTH
Chris

[jafo]

well it was from eurocar parts and they said it was oe, so that may be a good point, how much for a genuine one?

Just checked through my invoices and it was a walker one! Is that genuine??

[Rmachines]

If you have a blowing exhaust it will through the emissions right out ?

[zorro]

well it was from eurocar parts and they said it was oe, so that may be a good point, how much for a genuine one?

Just checked through my invoices and it was a walker one! Is that genuine??

Nope - i got mine from GSF  - when it was on it's way out my car started runnign rich and performance suffered, but i also got an error code.

A genuine one is a Bosch one direct from VW and costs around £100 

[Stu G]

give it a bit of a service. mine struggled to get through the emmisions. ok its only 8v but changing the plugs and oil along with the filter helped a long way.

[ben44]

if you have a high co reading and a perfect lambda and hc as you state, im afraid this means you need a new cat convertor!(expensive)

Look into replceing it with a sport cat as you have the perfect excuse!!